There are two small vacuum hoses coming from the throttle body. if your looking down at it the top one goes to the BCV located on the back wall and the other (the one that is a real PITA) goes back and has a check valve inline and connects to the hose going into the valve cover. I keep having the second hose that goes back to the valve cover coming off the throttle body. Check valve works fine and the other end stays on the end attaching to the valve cover, but the part that plugs into the TB keeps coming off. Anyone know what would cause this?